Filter processing is the application of a two dimensional data set of coefficients over a sampling area of an input image. Filter processing allows various effects to be applied on images, such as blurring, sharpening, or removing noise.
One method of applying a filter to an image is to use sample pixels surrounding a target pixel to calculate a final value for the target pixel. In particular, each sample pixel is multiplied with a corresponding coefficient in the filter, based on its position in relation to the target pixel. The products of all of the sample pixels and coefficients are summed to get the final value for the target pixel.